Method of forming seamless flooring

ABSTRACT

SEAMLESS SURFACE COVERINGS, E.G. SEAMLESS FLOOR COVERINGS WITH A MARKEDLY REDUCED INCIDENCE OF SURFACE PROTRUSIONS THROUGH THE RESINOUS OVERLAYER FROM PROJECTING DECORATIVE PARTICLES ARE DISCLOSED TO BE OBTAINABLE BY SPRAYING THE PARTICLES WHICH HAVE BEEN RANDOMLY DEPOSITED ONTO THE BASE COAT OR MATRIX WITH WATER TO WET THE PARTICLES AND THUS DECREASE THE NUMBER AND PROTRUSION EXTENT OF PROJECTING PARTICLES.

'sept 12, 1012 M.' ANDRESKI METHOD 0F FORMING sEAMLEss FLOORING OriginalFiled Oct. 19. 1967 501. VEA/7' 5.055

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United States Patent Olice 3,690,914 METHOD OF FORMING SEAMLESS FLOORINGMitchell Andreski, 32 Barbonsel Road, East Hartford, Conn. 06118Continuation of abandoned application Ser. No. 676,460, Oct. 19, 1967.This application Mar. 18, 1971, Ser.

Int. Cl. B44d 1/02 U.S. Cl. 117-26 11 Claims ABSTRACT F THE DISCLOSUREThis application is a continuation of Ser. No. 676,460, tiled Oct. 19,1967, now abandoned.

BACKGROUND OF THE INVENTION (l) Field of the invention This inventionhas to do with surface coverings and particularly combinations of stepsand materials providing outstanding surface qualities from both thepractical and aesthetic standpoint. In general, the invention isconcerned with method for forming surface coverings, particularly oorcoverings. Although the specification will be addressed primarily tofloor covering application, as presently the single most important useof my invention, it is to be remembered throughout the followingdescription that the invention is likewise applicable to the formationof coverings on walls, counter tops, table tops, stair treads, patios,pool decks, boat hulls, shelves and as metal finishing. Typicalsubstrates thus will include wood, ceramic, cementitious, metallic andplastic surfaces.

The invention is not appropriately classified as a painting techniqueinvolving as it does multiple coats of different materials andimportantly separate application of the particulate decorativecomponent.

More correctly, the invention is classified with seamless flooring, anindustry still in its infancy, which provides the consumer with floorsurfaces having the remarkable toughness of high polymers, thekaleidoscopic design variety of linoleum or tile, and the high polishand low maintenance properties normally associated with glass and allwith an easy applicability similar to modern paints.

(2) Prior art Seamless floor coverings are known. In general, thecommercially successful products utilize a polyurethane base coat or amatrix, to which is added a particulate decoration such as metal flakes,or parti-colored plastic chips, and over which is layered a tough glossyresin, such as a polyurethane, usually termed a glaze coat.

These products are generally completely organic solvent based and tendto shrink somewhat on evaporation of the solvent. Such polyurethanematrix coats may, on shrinking, tend to curl and pick up the substrateto which they are applied, particularly if it is a linoleum or tilesubstrate. This curling tendency results in unsightly edges and corners,and provides opportunity for water seepage under the lloor coveringwhich is unsanitary and otherwise undesirable.

Patented Sept. 12, 1972 A common problem in the formation of seamlessflooring is the difliculty of eliminating protruding decorativeparticles which may even protrude to a degree causing penetration of thefinishing coat. The usual method of applying the decorative particles isto scatter them randomly, e.g. by raining them onto the base coat. Thistechnique provides an attractive randomness of pattern, which is highlysought, but also provides a randomness of particle orientation whichoften results in certain of the particles being relatively elevated orlying on edge and, therefore, protruding from the matrix coat. Attemptsto flatten these protruding particles following application aregenerally unsuccessful, involving as they do ordering rearrangements ofthe random pattern and disruption of the matrix uniformity since it isnot yet hardened. In addition, the laymans attempt to accomplish suchliattening is often quite messy.

SUMMARY 0F THE INVENTION It is an object therefore of the presentinvention to provide a combination of steps and materials for the easyapplication to any surface of a seamless covering with reducedprotrusions of decorative particles and with a substantial absence of atendency to shrink or curl on drying. Other objects will appearhereinafter.

It has now been discovered that seamless surface coverings such asseamless flooring can be formed in a highly advantageous manner by amethod useful to the layman and do-it-yourself enthusiasts and whichemploys a positive step to reduce protrusion of decorative particles. Ingeneral, the method of the invention is applicable to formation ofseamless flooring which is effected by depositing decorative particleson a previously applied and liquid matrix containing a resinous binderin an aqueous carrier in a manner normally tending to cause depositedparticles to protrude from the matrix surface sufficiently to interferewith the surface smoothness of a subsequently applied resinousoverlayer. The invention involves the novel step of wetting the surfacesof particles left protruding by the usual method with a liquidcompatible with the aqueous carriers such as water or water containing awetting agent, thus to reduce particle protrusion by increasing theainity of the aqueous based matrix for the normally hydrophobic particlesurface.

In preferred practice the matrix or under-layer coat first applied tothe flooring or other surface will be an aqueous mixture of athermosetting resin, particularly of an epoxy resin and the final coator overlayer will be a glossy resinous material such as a polyurethaneresin in an organic solvent solution. Typically the decorative particlesare broadcast randomly over the matrix to deposit thereon in a locallyirregular, but generally repetitive pattern.

Wetting of the so deposited particles is effected by misting, fogging orotherwise lightly spraying over the particles a water coating,suflicient to increase receptivity of the particles into the matrix butless than that ooding or disturbing the matrix surface and orderlyrandomness of particle pattern. Following settling or submersion of thedecorative particles the thermosetting resin is permitted to harden,i.e. cure and subsequent layers are added such as the organic solutionof a glaze resin and, if desired, a sealer coat intermediate the matrixand glaze to preclude solvent attack on solvent vulnerable components ofthe matrix-particle mixture.

BRIEF DESCRIPTION 0F THE DRAWINGS In the drawing the single figureillustrates schematically the stepwise formation of a floor coveringaccording to the present method.

3 DESCRIPTION OF THE PREFERRED EMBODIMENTS In terms of materials thepresent invention utilizes a matrix resin, an overlayer or finishingresin and decorative particles, together with a sealer resin inpreferred practice.

The decorative particles are those conventionally einployed in seamlessflooring. As such they may {be inorganic, e.g. metallic or asbestosmaterials or organic, e. g. synthetic organic polymers. Obviously,`great variation in colors, configuration and cost can be had among suchdecorative materials. In general, the size of decorative particles willbe less than We" in greatest dimension. Rectangles, squares, circles,semicircles, triangles, crescents and other regular and irregulargeometric shapes in solid or variegated coloration and of variousthicknesses may be employed. Most often the particles will berectilinear, essentially planar and less than 1,66" on a side. Amongsuitable metal particles are chips of aluminum, copper and tin. Amongsuitable plastic particles are chips of vinyl polymers especiallypolymers of vinyl chloride, styrene and ethylene or propylene monomersas well as acrylic acid and acrylic acid derived monomers and copolymersof the foregoing with each other and other copolymerzable monomers. Thedecorative particles are deposited on the matrix layer usually by raimngor gravity effect, if suitable, e.g. for decorating floor coverings, orby ballistic techniques if particle flow is against gravity. In kitform, ready for do-it-yourself use, the chips or decorative particlesare packaged in a bag or other container in an amount to cover theexpected coverage of matrix resin.

The matrix layer, so-called because it envelops and surrounds thedecorative particles is the rst coating formed on the surface to becovered. This is Step l in the figure. This first coating should beadherent to the substrate, be it plastic, wood or mineral, non-curlingand nonshrinking on drying, easily handled, nontoxic and have areasonable workin-g period. I have found that aqueous carrier mixturesof air curing epoxy resin have all the requisite properties and at nottoo great a cost. Other thermosetting resins such as phenolics,melamines and urethanes are prone to shrinkage on evaporation of theirsolvent carrier, lack adhesion or may be toxic in closed spaces and givedermatological difficulties. Thus, although any of these resins may beused, I generally employ an epoxy resin system. By the term epoxy resinherein I refer to resins characterized by the presence of oxiraneoxygen, i.e.

and such resins which undergo progressive crosslinking polymerizationeither with themselves or with crosslinking agents to form tough,adherent coatings which are clear and hard. This class of resins is wellknown and it will suice to indicate that in general useful epoxy resinsare those derived from polyhydroxy compounds and epichlorohydrin, e.g.from dihydric phenols particularly polynuclear dihydric phenols such asthe bisphenols. A commercially available and highly useful resin is thatknown as the diglycidyl ether of bisphenol-A, i.e. 2,2- bis(4-hydroxyphenyl) propane. Suitable epoxy resins have the repeating unit-D-O-E-O in which D is the radical residuum of a polyhydric phenol and Eis the radical residuum of epichlorohydrin.

The above epoxy resins may be cured by reaction with polyfunctionalcompounds such as polybasic acids, acid anhydrides, polyamines andcomplexes such as boron trilluoride. In general hardeners are used ineffective amounts e.g. 0.] to by weight of the epoxy resin. The termthermosetting epoxy resin herein refers to epoxy resins which will cureto hardened states on exposure to air and/or heat because of theirintrinsic hardener.

A full description of epoxy resins and hardeners useful herein may befound in U.S. Pat. 3,238,087 to S. Norwalk et al.

As stated these epoxy resins are preferably employed as water basedproducts. Because they are water insoluble, aqueous mixtures of epoxyresins may be termed emulsions or suspensions or simply, and moregenerally mixtures. Preparation and characteristics of such products aredetailed in U.S. Pat. 3,020,350 to S. Norwalk. It is preferred to employa mixture having a viscosity enabling easy trowling or spreading overthe surface to be covered, stiff enough to remain in place but fluidenough to spread easily. Thixotropic additives such as polyamidemodified alkyd resins may be employed in the matrix material to givedesired handling qualities. In kits for the home owner the epoxy resinwill be typically in a can or other sturdy container in an amountappropriate for a predetermined surface area. Generally the epoxy systemwill be two component so that the cure reaction begins only on mixing ofthe two components, applying to the surface and exposing to air.

While the base coat or matrix cures e.g. in an hour the decorativeparticles are deposited thereon. This is Step 3 in the figure. Matrixviscosity should be such as to not inhibit penetration of the matrixsurface by and resultant submersion of the particles.

Advantageously following smoothing of the matrix on the surface, thematrix may be water wetted for better reception of the particles. Thisis Step 2 in the figure. Water treatment may be a relatively heavyapplication e.g. flooding or flushing but puddle formation or disruptionof the matrix surface smoothness should be avoided. This wetting may beeffected by spraying and the water used may include wetting agents, tobe described hereinafter.

Following deposition of the particles either directly on the matrixcoating or on a superficial water layer on the matrix coating theparticles are themselves wetted, suitably with a water spray. This isStep 4 in the figure. The water spray may be obtained from aconventional garden spray gun, paint sprayer or other device capable ofgenerating small particles of water. I ust enough spray to water wet theparticle surface adjacent the matrix is required. This coating isbelieved to so alter the surface properties of the particle sufficientlythat full reception of the particle into the matrix is readily effected.

The water used in Step 4 may include a wetting agent by which term ismeant a compound which lowers the surface tension of water below 72dynes/cm.

Among wetting agents useful in the water spray are ionic, nonionic orcationic, organic or inorganic wetting agents. Concentrations in aqueousmedia will range from just significant to 2% to 40% and higher, i.e.sufficient to lower water surface tension.

In general, suitable non-ionic agents are those which may be produced bythe introduction of alkylene oxide group into an organic hydrophobiccompound or group having an aliphatic or aromatic structure. The hydrophobic organic group generally contains at least 8 carbon atoms and upto about 30 carbon atoms. Condensed with the hydrophobic group are atleast 5 and preferably up to about 50 alkylene oxide groups. It ispreferred to use the polyoxyethylene eondensates derived from ethyleneoxide. Among the nonionic detergents, it is preferred to use thepolyalkylene oxide condensates of alkyl phenol, such as thepolyoxyethylene ethers of alkyl phenols having an alkyl group of atleast about six, and usually about 8 to 12 carbons, and an ethyleneoxide ratio (number of moles per phenol) of about 7.5, 8.5, 11.5 or 20,though the number of ethylene oxide groups will be usually from about 8to 18. The alkyl substituent on the aromatic nucleus may bedi-isobutylene, diamyl, polymerized propylene, dimerized Cs-C? olefin,and the like.

(including room temperature) chemistry or the presence of a Othersuitable wetting agents are the polyoxyalkylene esters of organic acids,such as the higher fatty acids, rosin acids, tall oil acids, or acidsfrom the oxidation of petroleum, et cetera. These polyglycol esters willcontain usually from about 12 to about 30 moles of ethylene oxide or itsequivalent and about 8 to 22 carbons in the acyl group. Suitableproducts are refined tall oil condensed with 16 or 20 ethylene oxidegroups, or similar polyglycol esters of lauric, stearic, oleic acids,etc.

Additional non-ionic wetting agents are the polyalkylene oxidecondensates with higher fatty acid amides, such as the higher fatty acidprimary amides, monoand diethanolamides. Suitable agents are coconutfatty acid amide condensed with about 10 to 50 moles of ethylene oxide.The fatty acyl group will have similarly about 8 to 22 carbons, andusually about 10 to 18 carbon atoms, in such products. The correspondingsulfonamides may be used also if desired.

Other suitable polyether non-ionic wetting agents are the polyalkyleneoxide ethers of high aliphatic alcohols. Suitable fatty alcohols havinga hydrophobic character, preferably 8 to 22 carbons, are lauryl,myristyl, cetyl, stearyl and oleyl alcohols which may be condensed withan appropriate amount of ethylene oxide, such as at least about 6, andpreferably about l to 30 moles. A typical product is oleyl alcoholcondensed with about l2, 15 or 20 moles of ethylene oxide. Thecorresponding higher alkyl mercaptants or thioalcohols condensed withethylene oxide are suitable also. The water-soluble polyoxyethylenecondensates with hydrophobic polyoxypropylene glycols may also beemployed.

Further suitable non-ionic materials are the higher fatty acidalkanolamides, such as the monoethanolamides, diethanolamides andisopropanolamides wherein the acyl radical has about l0 to 14 carbonatoms and amine oxides. Examples are coconut (or equivalent lauric),capric and myristic diethanolamide, monoethanolamide andisopropanolamide, dodecyl dimethyl amine oxide and dimethylacetoxyalkylamine oxide where alkyl is C11-C14.

Other suitable agents are anionic aromatic materials, e.g. water-solublehigher alkyl aryl sulfonates particularly those having from 8 to aboutl5 carbon atoms in the alkyl group having a mononuclear aryl nucleus,such as toluene, xylene, or phenol. The higher alkyl substituent on thearomatic nucleus may be branched or straight-chained in structure,examples of such group being nonyl, dodecyl and pentadecyl groupsderived from polymers of lower mono-olens, decyl, keryl, and the like.

Illustrative of suitable aliphatic anionic agents are the normal andsecondary higher alkyl sulfate detergents, particularly those havingabout -8 to 15 carbons in the fatty alcohol residue, such as lauryl (orcoconut fatty alcohol) sulfate. Other suitable detergents are thesulfuric acid esters of polyhydric alcohols incompletely esteried withhigher fatty acids, e.g. oleic acid ester of isothionic acid; the higherfatty acid (e.g. coconut) ethanolamide sulfate; the higher fatty acidamide of amino alkyl sulfonic acids, e.g. lauric acid amide of taurine;and the like.

Typical specilic examples are: the sodium salt of a sulfate ester of analkylphenoxypoly (ethyleneoxy) ethanol, the ammonium salt of thissulfate ester, sodium methyl oleyl taurate, sodium alkyl naphthalenesulfonate, alkyl acyl sodium sulfonate, sodium tetrahydronaphthalenesulfonate, sodium alkyl aryl sulfonate, alkyl amido sulfate,cocomonoglyceride sulfate, dodecylbenzene sodium dodecyl diphenyl oxidedisulfonate, sulfonated castor oil, polyethoxyalkyl phenol sulfonatetriethanolamine salt, sodium triethanolarnine alkyl aryl sulfonate,magnesium lauryl sulfate, potassium lauryl sulfate, sodium lauryl ethersulfate, ammonium lauryl ether sulfate, sodium tallow sulfate,dodecylbenzene sodium sulfonate, oleyl methyl tauride, ammonium laurylsulfate, amide sulfonate and the like.

Other suitable synthetic detergents are cationic agents such as theamines particularly primary fatty amines such as lauric amine, myristicamine, palmitic amine, stearic amine, oleyl amine, linoleyl amine, cocoamine and tallow amine. Also N-fatty propylene diamine and heterocyclictertiary amines as well as fatty halides, e.g. stearyl dimethyl benzeneammonium chloride, dodecylbenzene chloride, lauryl pyridinium chlorideand sulfates, e.g. lauryl pyridinium bisulfate can be used.

In Step 5 of the figure a sealer or barrier coat is put on. It is thefunction of this coating to protect the decorative particles and thematrix coat, if necessary, from attack by the finishing or glaze coat.It is preferred to employ an aqueous based resin as the barrier coat.Numerous materials are useful including alkyds, acrylics and vinylpolymer solutions and suspensions. Preferred resins are water solublepolyurethanes.

'In Step 6 of the drawing the finishing or glaze coat is added. Thiscoat is typically an organic solvent solution of a polyurethane but maybe any resin alfording high gloss, toughness, detergent resistance andlong wearing properties.

The sealer and glaze coats as stated are preferably polyurethane. Theterm polyurethane herein has reference to synthetic organic polymersderived from reaction of polyisocyanates with compounds having aplurality of active H atoms typically various polyols. Polyurethanes maybe classified according to their cure mechanism e.g. as moisture curing"from the presence of excess isocyanate groups which are moisturereactive to cure the resin or "two component from the curing reactionbetween two different materials one having an excess of isocyanategroups and the other active hydrogens e.g. in an hydroxyl group orIdrying oil" type in which cure reaction is through unsaturation ofalcoholized drying or semi-drying oils reacted with a polyisocyanate.

Polyurethane resins of the moisture curing type can be prepared from apolymer having at least two groups possessing active hydrogen atoms suchas hydroxyl rich polyesters or polyethers, and an organicpolyisocyanate, such as tolylene diisocyanate present in substantialexcess e.g. 10 to 110 percent greater than the stoichiometric amount.

Polyurethane resins of the two component type are preparable by reactinga substantial excess of organic polyisocyanate with a compound having anumber of groups containing an active hydrogen, such as an alkane polyole.g. hexane triol; the other component is generally a polymer having anumber of groups containing an ac-4 tive hydrogen such as an hydroxylrich polyester or polyether or the like. These two components are mixedjust before use. The isocyanate groups of the first component react withthe active hydrogens of the second component effectively crosslinkingthe components into a tough durable coating. The resin system can becatalyzed with driers such as cobalt naphthenate or stannous octoate.

The polyurethanes of the drying oil type are urethane oils produced byreacting an alcoholized drying or semidrying vegetable or marine oil, oroil acid, with an organic polyisocyanate. Among suitable oils arelinseed oil, perilla oil, safflower oil, soybe'an oil, tung oil, castoroil, dehydrated castor oil, octicica oil and the like as well as oilacids of such oils. These oils are alcoholized with a polyol such as oneof the alkylene glycols e.g. ethylene glycol, propylene glycol,hexamethylene glycol and pinacol or triols such as glycerol,trimethylolpropane, hexanetriol, as well as erythritol, pentaerythritol,mannitol and other polyhydroxy alcohols having from 2 to about l0hydroxy groups and 2 to 20 carbon atoms. Following alcoholysis the oilsare reacted with an organic isocyanate in known manner.

In preparing the foregoing polyurethanes preferred isocyanates includealkylene, cycloalkylene, aryl and haloaryl diand triisocyanatesgenerally containing from 4 to 20 carbon atoms e.g. hexamethylenediisocyanate, cyclohexyll,4diisocyanate, tolylene diisocyanate, diphenylmethane 4,4'diisocyanate, biphenyl 4,4diisocyanate,

naphthalene diisocyanates, 1,2,4-benzene triisocyanate,butanel,2,2triisocyanate, triphenyl diisocyanate, ethylene diisocyanate,and chlorophenyl-2,4diisocyanate and the like.

The sealer and glaze coats are applied following hardening of the matrixlayer with the decorative particles embedded therein. Application is bymeans of a roller, trowel or other device enabling smooth spreading ofthe resinous solutions over the matrix surface.

EXAMPLE Flooring to be resurfaced and having a covering of linoleum isrst thoroughly cleaned to remove wax and polishes and apparent cracksare filled. A surfacing kit including two containers of aqueous epoxyresin, a container of particolored vinyl plastic chips, a container ofpolyurethane in water solution and a container of polyurethane in xylenesolution is used. The two containers of epoxy resin are thoroughlymixed, initiating a curing reaction allowing a working time of about onehour. The aqueous epoxy having the viscosity of cream and at about 70%by weight solids is roller coated or troweled across the linoleumsurface to form a flood coat. The ilood coat is allowed to dry and theresin cure. This requires about one hour. After the hour or when theflood coat will support a persons weight, a second layer of epoxy resinis laid down, as a matrix. Immediately a water spray is applied to thematrix to thoroughly wet the surface without puddling or locallyflooding. The vinyl chips are then broadcast by being tossed upward andallowed to oat downward onto the wet matrix surface. On settling of thechips a line water mist is played over them to lightly but completelywet their surfaces to insure settling of the chips into the matrixlayer. The applied surfacing is then allowed to dry for about twelvehours at about 70 F. Thereafter loose chips are swept from the lloor andthe area is sanded if desired for increased smoothness. The sealer coatis now applied consisting of a polyurethane resin in aqueous solution.Application is at a thickness covering all deposited chips. After thesealer coat is dry the glaze coat is applied consisting of several e.g.three applications of a catalyzed polyurethane resin in an organicdiluent with intermediate sanding and vacuuming steps. The presence ofthe sealer resin layer prevents the solvent in the glaze from attackingthe vinyl chips and muddying their coloration. No curling or warping ofthe finished oor covering was noticed after six months of use.

CONTROL The example was duplicated but omitting the water spray beforeand after decorative chip deposition. Numerous chips protruded upwardlysufficiently from the matrix to render final finishing operationsditlicult and high surface smoothness nearly impossible to obtain.

I claim:

l. The method of forming a surface covering such as a floor covering inplace which includes depositing decorative particles on a previouslyapplied and liquid matrix containing an epoxy resin in an aqueouscarrier in a manner normally tending to cause deposited particles toprotrude from the matrix surface sufficiently to interfere with thesurface smoothness of a subsequently applied resinous overlayer andspraying water onto protruding particles to wet the particle surfaces toreduce the protrusion thereof.

2. Metnod according to claim 1 including also curing said epoxy resinfollowing deposition of particles thereon.

3. Method according to claim 1 including also forming said overlayer bycoating the matrix containing deposited particles with a solution of apolyurethane resin and evaporating the solvent from said solution.

4. Method according to claim 1 in which depositing includes randomlydistributing a quantity of decorative particles onto said matrix bybroadcasting the particles adjacently above the liquid matrix.

5. Method according to claim l including also spraying water over thematrix before particle deposition.

6. The method of forming in place a surface covering on a wood, ceramic,cementitious, metallic or plastic surface whicn includes coating thesurface to be covered with an adherent curable epoxy resin in an aqueouscarrier to form a matrix, broadcasting decorative particles over thematrix to randomly deposit same on the matrix surface, water sprayingthe deposited particles to increase their penetration into the matrix,curing the epoxy resin with the particles therein and coating the curedepoxy resin with a resinous overlayer.

7. Method according to claim 6 including also waterwetting the epoxyresin coating prior to application of decorative particles thereto.

8. Method according to claim 7 in which the resinous overlayer comprisesa polyurethane resin in organic solvent solution and including alsocoating the cured epoxy resin with a water base resin and drying priorto application of the organic solvent based polyurethane.

9. Method according to claim 7 including also lowering the surfacetension of the water to be water sprayed prior to spraying over thedeposited particles to aid in wetting said particles.

10. Metnod according said epoxy resin.

1l. The method of forming in place a surface covering on a wood,ceramic, cementitious, metallic or plastic surface which includescoating the surface to be covered with an adherent curable epoxy resinin an aqueous carrier to form a matrix, broadcasting decorativeparticles over the matrix to randomly deposit same on the matrixsurface, water wetting the deposited particles to increase theirpenetration into the matrix, curing the epoxy resin with the particlestherein and coating the cured epoxy resin with a resinous overlayer.

to claim 7 including air curing References Cited UNITED STATES PATENTS2,776,914 l/ 1957 Faulwetter 94-3 X 2,987,104 6/ 1961 Benedict 156-2983,174,977 3/ 1965 Hoiberg et al 94-3 X 3,238,087 3/1966 Norwalk et al.161-184 X 3,311,515 3/1967 Weller et al. 156-71 3,334,555 8/ 1967 Naginet al. 94-3 3,401,069 9/1968 Lorentzen 156-71 3,406,618 10/ 1968 Bowman94-3 X 3,407,165 10/1968 Oepkes 94-3 X 3,446,644 5/ 1969 Murphy 117-26 X3,549,404 12/ 1970 Liberti et al 117-29 X 3,552,988 l/ 1971 Boiari117-29 X 3,562,076 2/ 1971 Lea 94-3 X ROBERT F. BURNETT, PrimaryExaminer I. C. GIL, Assistant Examiner USS. Cl. XR.

94-3; 117-16, 2l, 25, 29, 33, 62.1, 64, 100 R, 100 M, D; 161-5, 162,184, 190

